The use of disposable elastomeric ambulatory infusion devices have gain wide acceptance due to its ease of use, safe and effective means of drug delivery in non hospital based settings.
The manufacture of such devices has been extremely challenging with respect to achieving accurate flow rates. The flow rates are primarily governed by the combined effect of the pressure generated when the device is filled and a flow control tube in accordance to Bernoulli's theorem. Depending on the extent of unevenness in the wall thickness of the fluid container, the filling of medication fluid into the fluid container may result in non uniform expansion in which lesser than intended extent of the surface area is effected in the force pushing the fluid. This complicates the process of matching flow tube to pressure which is critically important in order to produce accurate flow rates.
Another drawback resulting from the variation in pump pressure is that it makes simultaneously multiple filling impractical, as weaker pumps would fill up easily and end up with larger volume of medication than stronger pumps.
There are further limitations in the use of elastomeric pumps in situations where infusions are not required immediately after filling. For example, a patient may need multiple doses over a long duration. The filled delivery apparatuses that are used later may not have the intended flow rates as the pressure generated by the elastomer elements would typically change with time.